Polymerization electrophilic

Figure 6. Electrophilic polymerization of thiophene. Initial 71-bonding, formation of radical cation, electrophilic addition.

Scheme 6 Formation of hyperbranched thin film nanocomposites using an electrophilic polymeric reagent 14 and a nucleophilic amine-functionalized PAMAM dendrimer 15...

Cationic polymerization is initiated by acidic substances. Bronsted acids and particularly Friedel-Crafts halides (viz., their complexes), which are adds in the Lewis sense, are excellent and widelyused initiators for electrophilic polymerizations. The number of cationoid substances which have been described to possess electrophilic polymerization activity is slowly increasing. These materials will be briefly surveyed here. 

Also, it is well known that HgSC and HC104 are efficient cationic initiators. Nitromethane (17) and a number of other simple cationoid substances mentioned earlier can also function as electrophilic initiators. These observations are significant and should modify our concept of electrophilic polymerizations. 

There is no concrete evidence that tin or lead alkyls can initiate coordinated anionic polymerization, and this is in accord with their covalent bond character and low electrophilicity. Polymerizations which have been initiated with these catalysts are most probably free radical in nature. 

There is a good chance for copolymerization if the two monomers exhibit similar reactivities toward a common growing species. Both isobutylene and P-pi-nene exhibit hi reactivities under electrophilic polymerization conditicms. And, significantly, the propagating species that participates in these polymerizations are very similar ... 

Electrophilic Polymerization. The ring-opening polymerization of 2-phenyl-l,2-oxaphoapholane, 1, a five-membered deoxophostone is Induced by a cationic initiator to give a white powdery material, polyCphenyltrimethylenephosphine oxide 11 (13). Initiators like... 

The electrophilic polymerization of for example. Involves stable phosphonlum species which reacts with monomer via an Arbuzov type reaction to Induce a C-S bond scission leading to a phosphine sulfide unit. 

The electrophilic polymerization of this type is often referred to as Friedel-Crafts polymerization. Examples are polymers obtained from near equimolar feeds of terephthalic acid as dicarboxylic acid and 4-phenoxy-phenyl sulfone, or 4-biphenylyl sulfone, respectively. Usage of 4,4 -di-phenoxybenzophenone yields a poly (ketone). 

It was shown in [249] on the base of quantum-chemical calculations and experimental data that acidic force of electrophilic catalysts is the measure of activity and stereospecificity of their action under cationic polymerization. Increase of acidic force of electrophilic polymerizations catalysts promotes increase of their activity but decreases process selectivity. For example, in [250] piperylene oligomerization initiated by etherates of titanium chloride and aluminum is studied. AlCl3 0(C6Hs)2 gives high yield and molecular mass of product and received oligopiperylene however has low unsaturation. 

A process for the preparation of aryl polyether-polyketones by electrophilic polymerization has been disclosed [260]. The polymers, having excellent high-temperature resistance, are prepared by the reaction of carboxylic acid halides in... 

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